Hi Experts,

I have set-up mail server on 192.168.6.1 (Redhat 6.1 Santiago). This server is in Russia. The server has no internet connectivity, so I have configured Mail Relay Agent on it as mail.x.com (In India) under /etc/postfix/main.cfg. I have made an entry for mail.x.com under /etc/hosts with ip to name binding. I am able to ping mail.x.com and also able to telnet to it on port 25 (SMTP) from this Russia server.
I then restart the postfix service and it comes up without any error message. When I send mail using mailx or sendmail, and then check the logs under /var/log/maillog, I get the below error message :-

to=<srijiv@gmail.com>, relay=none, delay=1004, delays=999/0.02/5.1/0, dsn=4.4.3, status=deferred (Host or domain name not found. Name service error for name=mail.x.com type=MX: Host not found, try again)

The resolv.conf entry has a global dns server configured under it. But to my understanding, when I am able to telnet and ping this mail.x.com server, then why is the name resolution failing ?

Is there a way to get around this problem.

Appreciate all your help.

Bad idea - that domain exists Also, it's not clear where you are trying to send mail from or to, or which is trying to lookup your bad hostname.

Hi descendant_command,

Thanks for looking into this.

mail.x.com where 'X' is my company domain name. I have mapped mail.x.com to one of the Public ip assigned to our company. So if I make any request to this public ip, it gets re-directed to my mail-server. The private if for this mail-server is 192.168.1.5.

We have lease line connectivity between Bangalore and Russia.

I am trying to send mails from Russia Server to different recipients who have accounts in gmail, yahoo and also in my company domain. These settings are configured under '/etc/postfix/generic'. Because Russia Server does not have internet connectivity, so I want to send mails first to my mail server here in Bangalore, India and from there relay it to different recipients.

For all the co-locations which has Internet connectivity, I have configured the Relayhost under '/etc/postfix/main.cfg as the Public ip of my mail server in India. For co-locations which don't have internet connectivity, I have mentioned the private ip for the same. Routing is in place, as I am able to telnet on the private ip for the mail server on port 25 from those co-locations.

When I send a test mail, it throws me with the above mentioned error. Please let me know if I am missing something here.

OK.

It seems your relay transport (on the russia server) is not configured correctly
It should be trying to relay any mail via your india server.

This is how the /etc/postfix/main.cfg looks like

myhostname = W2W-SGX1
mydomain = x.com
myorigin = x.com
inet_interfaces = all
inet_protocols = all
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
relayhost = mail.x.com

When I send a test mail from Russia Server,
# echo "TEST" | sendmail "TEST" srijiv.w2w@gmail.com
in the logs I see:-
9 11:49:33 localhost postfix/smtp[2029]: 4FCE21A0633: to=<srijiv.w2w@gmail.com>, relay=none, delay=134919, delays=134909/0.01/10/0, dsn=4.4.3, status=deferred (Host or domain name not found. Name service error for name=mail.x.com type=MX: Host not found, try again)

Ah ok, that is making more sense.
It would seem to be the MX lookup that is failing.
If you put square brackets like [mail.x.com] it suppresses the MX lookup and just uses the hostname.
Or you could simply use [192.168.1.5] or such.

If I put a square bracket as 'relayhost = [mail.x.com]' , The error message now is :-

Feb 9 12:12:48 localhost postfix/smtp[7937]: 9413D1A0630: to=<srijiv.w2w@gmail.com>, relay=none, delay=20, delays=0.03/0.01/20/0, dsn=4.4.3, status=deferred (Host or domain name not found. Name service error for name=mail.x.com type=AAAA: Host not found, try again)

If I put a host name in relayhost as 'relayhost = 192.168.1.5', the error message is:-

Feb 9 12:15:42 localhost postfix/qmgr[8707]: 68E511A064A: from=<root@x.com>, size=414, nrcpt=1 (queue active)
Feb 9 12:15:42 localhost postfix/smtp[8718]: 68E511A064A: to=<srijiv.w2w@gmail.com>, relay=192.168.1.5[192.168.1.5]:25, delay=0.45, delays=0.01/0/0.35/0.08, dsn=5.7.1, status=bounced (host 192.168.1.5[192.168.1.5] said: 554 5.7.1 <srijiv.w2w@gmail.com>: Relay access denied (in reply to RCPT TO command))

Still getting the error messages. Appreciate all your help.

No.
That is a new error message and means you are making progress

Your russia server is now working (although you should have sq brackets around the IP).

Now you just need to adjust your india server so it is not rejecting mail-to-be-relayed from your russia server.
Presumably, adding it to the $mynetworks should be sufficient.

Thank you so much for helping me out with this. It now makes complete sense. I completely overlooked the reject message from 192.168.1.5. I will now check that and will update you about this accordingly.

Appreciate that.